Tom Pennington/Getty Images(NEW YORK) -- Former President George H.W. Bush, who has been hospitalized for a month, got a “real shot in the arm” from being serenaded over the phone Friday by country music superstars the Oak Ridge Boys, spokesman Jim McGrath said.

“Barbara Bush requested that we call the President and sing to him! All of the Oak Ridge Boys are on vacation, but we all headed to our office upon hearing of this request,” said a statement from singer Duane Allen.

“We asked what song he would like to hear and he said ELVIRA so we blasted some oom pop a mau mau’s in the direction of Houston, Texas,” Allen said.

“I love him like a father, he’s always treated the Oak Ridge Boys like family,” Allen said in an interview with ABC News Radio from Nashville. “It was great to cheer him up and he’s such a dear friend and it made us feel good that he would even want to hear us sing.”

After “Elvira”, the band finished up with a rendition of “Amazing Grace.”

“Words cannot properly express how much The Oaks’ special performance meant to the President and the Bush family,” McGrath said in a statement. “This friendship goes back many years, and what happened yesterday gave the President a real shot in the arm as he, thankfully, continues to improve.”

Bush had been moved to the intensive care unit and placed on a liquids-only diet on Dec. 23 after a “series of setbacks” including a persistent fever, McGrath said. He was moved out of the intensive care unit and into a regular patient room at The Methodist Hospital on Saturday.

Two days after Christmas, Bush’s chief of staff Jean Becker sent an email to family and friends saying the octogenarian former commander-in-chief had no plans to go anywhere soon, and to tell everyone to “put the harps back in the closet.”

The 88-year-old former chief executive was admitted to Houston’s Methodist Hospital on Nov. 23, suffering from a lingering cough related to bronchitis.